Efficiently Removing Duplicates from an Array of Objects in JavaScript

Dealing with arrays of objects is a common task in programming. Sometimes, you encounter situations where you need to remove duplicates from an array based on a specific key. In this article, we’ll dive into a JavaScript solution for this problem.

The Problem

Imagine you have an array of objects, and you want to eliminate duplicate entries based on a particular attribute. For example, you might have a list of products and want to remove duplicates based on their product IDs.

The Solution

Let’s create a JavaScript function called removeDuplicatesBasedOnKey to tackle this problem efficiently. This function will take an array of objects and a key as parameters, ensuring that duplicates are removed while keeping the code simple and the time complexity low.

function removeDuplicatesBasedOnKey(array, key) {
  const seen = new Map();
  const result = [];

  for (const item of array) {
    const keyValue = item[key];

    if (!seen.has(keyValue)) {
      seen.set(keyValue, true);
      result.push(item);
    }
  }

  return result;
}

// Example: Removing duplicate products based on their 'id' key
const products = [
  { id: 1, name: "Product A" },
  { id: 2, name: "Product B" },
  { id: 1, name: "Product A" }, // Duplicate ID
  { id: 3, name: "Product C" },
  { id: 2, name: "Product B" }, // Duplicate ID
];

const uniqueProducts = removeDuplicatesBasedOnKey(products, 'id');

console.log(uniqueProducts); // Output: [{ id: 1, name: "Product A" }, { id: 2, name: "Product B" }, { id: 3, name: "Product C" }]

Conclusion

In this article, we’ve explored an efficient way to remove duplicate objects from an array in JavaScript, focusing on a specific key. The removeDuplicatesBasedOnKey function can be a valuable addition to your coding toolkit, making tasks involving data manipulation more manageable.

By employing a Map to keep track of seen key values, we maintain a low time complexity for the solution, ensuring it works well even with large datasets.